<html><head>
<style>
div {
  outline: 1px solid black;
}
</style>

</head><body>
You should see no red, only green<br>
  <div style="overflow: scroll; height: 200px; z-index: 2; position: relative; background-color: red;"></div>
    <div class="displayport" reftest-displayport-h="500" style="overflow: scroll; position: relative; margin-top: -200px; height: 200px;">
      <div style="z-index: 10; position: absolute; width: 100%; height: 500px; bottom: -300px;">
        <div style="height: 200px; background-color: lime;"></div>
      </div>
   </div>
</body></html>
